Gas-impervious



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cas-mrnavrousimmanent; AND rso'enss OF'PEEPARING No Drawing.

To all 107mm it may concern:

Be it known that weydairies GLETlVRIGHT and Vtnarm K; Qnncirnmmsn, respectivelya subject of the King 'of'Grcat-Britain and a citizn of the United Eltates, residing at Schenectady, county of Schenectady, State of New York; have invented certain new a nd l'lSe'flll Improvements :in Gas-Impermons Membranes: and Processes of Preparing Same, of which the following is a speci lication.

For some technical purposes a flexible sheet material which is impervious to gas is required which will withstand conditions for which common flexible materials are not suited. For example, rubber, varnished cambric and other materials, sometimes used for pneumatic bellows and diaphragms, become brittle at extremely low tempera tures, and moreover, rapidly deteriorate with age. Some of the internal animal membranes .are impervious to gases, but these membranes stifl'en and become hard and brittle when dried. Even when rendered limp by mechanical treatment, the product not only is weak but when wet re yerts to its original condition and becomes still upon subsequent drying.

In accordance with our present invention we have prepared a new, strong, pliable material, unaffected by low temperature and drying, by converting these animal membranes to a leatherdike product while introducing a noncorrosive, hygroscopic material, as, for example, ethylene glycol and glycerinc, which softens the membranes and causes them to remain'pliable even at the lowest temperatures encountered during severe winter conditions.

Among the various animal membranes which may be subjected to the practice of our invention, we prefer the lining of the throat and the bladder of cattle. Although the entire membranes may be used we pres fer the outer layer of the throat and the inner or outer layer of the bladder.

' The membranes are first of all washed *ith dilute ammonia, or a similar detergent, to remove secretions. They are thereupon dried while inflated. After drying the membranes are subjected for about four hours to a suitable dilute solution of a vegetable aiming agent, for example, a one per cent solution of gallic, or tannic acid, in

Application-filed January 28, 1921. Serial No. 440,778:-

water. This:operation is not essential al though I it I is desirable The essential step in the' practice of our intention =1'consists in l introducing' into the'if tissues the imembra'ne' a lnon corrosive', hygroscopic material; which has' 'a very low" freezi-ng: cpoint, that is,=--below -50 Fahr. While it is: possible 5 to obtain-1a rusable :m-a-- terial bya'i introducing i such a anateri-ah die rectly into the membrane tissue without a hardening treatment, the resulting product-' would be soggy and heavy, and hence unsuited for some technical use. We prefer, therefore, to give the membranes a treatment having an effect upon the tissues which is akin to tanning. The product although not strictly a leather is dry to the touch, light in weight, thinner walled than 'the raw membranes, but is still soft and pliable. The substance best suited to produce this pseudo-tanning effect is nigrosine. It is used conveniently in conjunction with a hygroscopic material, such as a mixture of glycerine and ethylene glycol, both of which are polyhydric alcohols.

The following solution has been used with so good results Parts by weight.

Glycerine 3O Ethylene glycol 5. 5 Nigrosine 2 lVater 70 Although glycerine alone has a beneficial effect, particularly in rendering the material pliable at low temperatures, it isnot as effective as the mixture of glycerine and ethylene glycol. The nigrosine has a tanning effect and acts also as a dye, giving the material a handsome black color.

The membranes should be well agitated in the solution during. treatment, a large quantity of the solution preferably being used. After having been subjected to this treatment, the excess moisture is removed, the membranes are dried, preferably while mechanically working or staking to in- 1 6 crease flexibility.

Membranes treated in this way have been subjected to temperature as low as -80 F. without stifiening. They remain pliable by use under dry conditions, are unaffected by 1 oil and are superior in aging qualities to other flexible membranes heretofore used.

What we claim as new and desire to se- Had ethylene glycol, said membrane being i111- pervieus to gas, pliable at low temperatures, and withstanding Wetting Without stifiening upon drying;

3. lne pr eess of ndering internal animu membrane eazguble of withsencling low temperatures and lr ing While retain ng pliability which eensists in treating szicl inenlbrane with e tanning agent, and a noncorrosive hygroscopic substance consisting in part of ethylene glycol.

at. The process of rendering animal membranes permanently flexible even when sub-- jected to extremely low temperatures or n clean, raw state, thereupon subject drying \vnieh consists in subjecting the 15211116 to a tannn urgent and thereupon treating tlQ same with a lDlI-IUHE o1 nigrosine, glyeerlne and ethylene glycol.

dry conditions and unuffec; cl by oil \z'hicl consists 1n drying said membr ne '1 same to a dilute vegetable iv. and finally treating said membi excess .1? a solution consisting by about TO parts water, 30 part 1,

parts ethylene gl 5 col, and 2 pa sine.

In Witness whereof, We have hereiuito SCt our hands this 27th day of January, JAllzlES G. E. WRIGHT.

VlNlTl-k 1*. till JIKJINBUSL. 

